and it goes into the phone side of the filter
Never plug an ADSL modem or router into the 'phone side of a filter.
There are no ADSL frequencies present on the 'phone connection (the filter blocks them), so your modem will not work.
It must be plugged into either the DSL socket on the filter, or with no filter at all.
Ade
Giving UKFSN/Entanet a try
DL Sync 4000kbps
UL Sync 448